The present invention relates to a valve for an opening of a pressure vessel. More particularly, it relates to a valve for such pressure vessel which has a housing and a resiliently deformable partition wall -- e.g. a diaphragm -- located in the housing and forming two compartments so that one of the compartments is filled with a liquid and has an opening in which latter the valve is mounted.
Valves for pressure vessels have been proposed each having a movable body member that is urged into a closed position by the resiliently expanded partition wall and urged into an open position by a spring acting in a direction substantially opposite to the direction in which said partition wall acts. It has, however, been recognized that when the liquid enters an outflow passage defined or in part bounded by the body member, at great speed, it exerts a component force upon the body member which tends to prematurely urge the latter into the closed position. Taking this into consideration, means have been proposed for preventing premature movement of the body member into the closed position, including a stem formed in the portion of the body member located in the pressure vessel and a passage provided in said portion so that the liquid flows through the passage, reacts against an inner end of the stem and provides a force operatively reacting against a valve head and urging the body member into an open position. While it is true that the above construction reliably performs its functions of preventing premature closing of the valve, it is very complicated and expensive.